Personal digital assistants (smartphones, personal assistant devices (PADs), tablet computers, etc.) comprise a display device of liquid crystal, organic electroluminescence (to be referred to as EL hereinafter) or the like. The display devices used for the personal digital assistants generally comprise additional functions including as that of a touch sensor.
The liquid crystal displays with a touch-sensor function, are subjected to noise immunity test to evaluate the immunity to external electromagnetic noise. An example of the noise immunity test is that a noise wave is radiated from an antenna onto a touch operation surface, and the occurrence of an erroneous touch operation (malfunction) due to the noise wave is checked.
For preventing the occurrence of malfunctions, it is necessary to form the detection electrode, which detects touch operations, to be insusceptible to noise waves reaching from outside. Here, shielding the detection electrode is one method. It entails the limited shielded region and the increase in cost for shielding.